Internal-combustion engine piston



SePt- 25, 1951 R. HUBER ET AL INTERNAL-COMBUSTION ENGINE PISTON BY l M z bf ATTURNE Ys m L H E m n MU 2 ww@ 2 a BO ad? 10,0304 Ffzy F1 a@ w? 6 O0 A E 2 Z Y w W. mi o 2 0 m N l m 70 I@ /0 Wl www? o0 .Z 009 00 m m M 5 ou 0 W m Xx, m m A l, m EN 1|. m l! l. NV xr .m m mm u w QW Mnm m m R. HUBER ET AL INTERNAL-COMBUSTION ENGINE PISTON Sept. 25, 1951 Filed March 29, 1950 "fifi/11111 vllllllillllll/ AINVENTDRS .u n F am T 0%.. R T mmv. ma PP ATTQRNEYS Patented Sept. 25,A `1951 INTERNAL-COMBUSTION ENGINE PISTON Robert Huber, Bellevue, and Prosper Vctor Flix, Paris, France, assignors to Societe dEtudes & de Participations: Eau, Gaz, Electricite, Energie, S. A. Geneva, Switzerland, a society of Switzerland Application March 29, 1950, Serial No. 152,722 In France April 8, 1949 The present invention relates to internal combustion engine pistons and is more particularly but not exclusively concerned with free pistons for such machines, i. e. pistons the length of stroke of which depends upon the balancing of the motive and resistant energies to which it is subjected and not upon the operation of a mechanical system.

Free pistons are known which include, inside the portion of the cylindrical side wall thereof which adjoins the piston end wall and is fitted with packing rings, a cylindrical partition substantially coaxial with said side Wall.

The object of our invention is to obtain in a simple manner an efcient cooling of the end wall of a piston of this kind, and to prevent breaks in the vicinity of the place where the piston end is connected to the side wall thereof.

According to our invention, in a piston of this type, the space between its cylindrical side wall and the cylindrical inner partition is closed at its rear end by a transverse partition, thus forming a chamber which is partly filled with a cooling liquid and inlet and outlet apertures for this liquid are provided in said cylindrical partition on either side of a transverse inner partition and at a distance both from the piston end wall and from said first mentioned transverse partition, front and rear pockets being thus created in said chamber in which is housed a mass of cooling liquid.

Preferred embodiments of the present invention will be hereinafter described with reference to the accompanying drawings, given merely by Way of example and in which:

Figs. l to 4 inclusive show, by way of example, four different embodiments of pistons made according to our invention, each of these figures being a piston axial section; V

Fig. 5 is a diagrammatic sectional view of the left hand portion of an autogenerator having opposed free pistons with conduits for the inflow and the outflow of the liquid for cooling the motor piston belonging to the movable unit of said portion of the auto-generator.

Each of the pistons shown in the various iigures and which constitutes a motor piston of a free piston system includes an end wall I the front face of which limits the motor space of the motor cylinder in which this piston is working. This piston end wall is made of relatively great thickness to enable it to support the high pressures which act thereon when the internal combustion engine is in operation. v

The periphery of the piston end WallV l Qon- 5 claims. (C1. 12s-41.36)

nected to a cylindrical wall portion 2 the outer surface of which cooperates with the cylindrical inner surface of the motor cylinder. Packing rings 3 are housed, in the usual manner, in this cylindrical wall. Part 2 is made of reduced thickness so as thus to maintain a certain elasticity which enables it to follow, up to a point, the expansions to which the' piston is subjected by its heating during operation of the engine. The critical place, where breaks easily occur, is constituted by the circular junction zone a. Despite the elasticity of the side wall 2 of the piston, joint a and the surrounding portionsl must be very efficiently cooled. The Way of obtaining this cooling will be hereinafter described.

As part 2, due to its reduced thickness, is not capable of transmitting the stresses exerted upon the piston end wall I,' a cylindrical partition'is provided inside this wall 2 and substantially in coaxial relation therewith, this partition 4 being generally of greater thickness than wall 2 and having preferably a diameter equal to at least one half of the diameter of side wall 2, partition 4 being intended to transmit at least a great portion of the stresses acting upon the piston end wall.

In order to ensure cooling of the piston about zone a, according to an important feature of our invention, the space between side wall 2 and partition 4 forms a chamber b partly filled with aV cooling liquid, for instance oil, and for this purpose, this space is closed at the rear by a transverse partition 5 located at a substantial distance from end wall I and even preferably at the rear of the zone in which packing rings 3 are located.

Inlet apertures 6 and outlet apertures 1' are provided in partition 4 for the cooling liquid, these apertures being located at a distance'both from the piston end wall l and from rear partition 5. We thusobtain, in chamber b, front and rear pockets adapted alternately to receive, in the course of the reciprocating movement of the piston, a mass of, cooling liquid which cannot escape through the inlet and outlet apertures of chamber b. v

In order to permit free expansion of the cylin-r drical side wall 2 with respect to partition 4, partition 5 is made either rigid with only wall 2 (see Fig. 2 and Fig. 4) or rigid with only partition 4, or again partly with Wall 2 and partly with partition 4 (see Fig. 1) and in all cases We provide packing means which make chamber b liquidtight while allowing for a limited axial sliding 3 of the rear end of wall 2 with respect to partition 4.

We further provide, inside partition 4 and between the two sets of cooling liquid inlet and outlet apertures '6 .and 1 a transverse partition 9 which thus `forms immediately behind the central portion of the piston end wall I, a cooling liquid inlet chamber c. to this chamber c, a feed conduit I is provided, which opens into this chamber, the end of this conduit projecting preferably from partition 9 into chamber c so that, during the movement of the piston toward the right, a mass 'of liquid gathers about this projecting end and is thus prevented from iiowing back into feed conduit I0.

The end of conduit I0 which penetrates into conduit c may be given the shape of a nozzle, as shown by Fig. l. According to another embodiment illustrated by Fig. 4, we provide, at the outlet end of conduit I Il, a deflecting plate II which radially deflects the cooling liquid which is ibeing ysupplied in an axial direction. This kdeiiection 'prevents the cooling liquid which is being fed from impinging directly against the center of the piston end wall.`

In order constantly to Aevacuate a portion of the cooling liquid, conduit I0 is 'surrounded by an .evacuation .conduit I2 and the interval between conduits I'Iland I12 is connected with the outlet apertures 'I' of chamber b. The inflow of the cooling liquid through conduit I0 and its outffow through conduit I2 may take place in the way indicated 'by Fig. 5. This gure shows the left hand portion of an. auto-generator having opposed free 4pistons and which includes on the one hand a motor cylinder I3 in which the motor piston according to the. invention is working and on the other hand a compressor cylinder If4 divided into two chambers vby a2 compressor piston I5 rigid with the above mentioned motor lpiston so as to formtherewith a. movable unit. The Lchamber located on the right hand side of piston I5 constitutes the compressor space. proper, this space being provided with suction valves I6 and discharge valves IfT, while the space located on the left hand side of this same piston constitutes a return energy pneumatic accumulator.

In order to ensure inflow andl outflow ofy the cooling liquid, we x, on the left hand wall I3 o1- cylinder I 4, a tube I9. the inner end 20 of which coaxially surrounds tube I 2, which is rigid with the movable unit, a stuliing box or other packing means 2| being provided between the end 20 of tube I9 and said tube I2. Furthermore, we hx to the cylinder, on the inside ofl tube I9y and coaxially therewith, a second tube 22 which extends into tube I`0. The outer end of tube I9 communicates with a. cooling; liquid exhaust conduit. 23, while: the outer endv of' tube 22 is connected with a cooling liquid. feed conduit, 24. Of course,l all these last mentioned tubes. I9, 22, 23, and 24 are stationary.v and do. not participate in the reciprocating movement of the movable unit.

The cooling liquid injected through tube 22 into tube I-Il thus iiows into chamber c adjacent to the central portion of the end wall I ofV the motor piston.v 'Ihis liquid then enters chamber b. through apertures 6,. The liquid, which only partly fills chamber informs therein a liquid mass which has, during the movement of the piston and due to the inertia ofthe liquid, a reciprocating movement, the velocity of which withV reference to the piston is practically equal to the vei'ocity of the piston itself.' Consequently', oil i'sviolently thrown against they piston end Wall,

In order to feed liquid y which ensures a very eflicient cooling, further reinforced by eddies formed inside the liquid mass. It should be noted that these movements of the liquid mass are particularly intensive in a free 'piston which is subjected, when in the vicinity of its dead center points, to high retardations and accelerations.

Besides, the shape of the inner face of the piston end wall I close to zone a is chosen in such manner as to obtain maximum eddying in this Zone.

The liquid mass which is formed in chamber c undergoes analogous movements and also has .an intensive cooling eiiect when it is thrown against the central portion of the piston end wall.

The excess of cooling liquid supplied through tube I0 is constantly evacuated through apertures I and the interval between tubes I0 and I2, so as thus to pass into tube I9 from which it flows out through conduit 23.

The motor piston being preferably made of steel, it is advantageous, in order to facilitate its manufacture, to make it of several elements. Thus, according to Fig. l, this piston. is essentially constituted by two elements d and e, portion d including end wall I, partition 4, a portion of wall 2 and a portion of wall 5, whereas element e includes most of wall 2 and a portion of wall 5. The two elements d and e are fixed together by means of a weld joint 25. The whole of the motor piston thus constituted is xed, for instance by means of bolts, to rod 26, which connects the motor piston with compressor piston I5. Wall 9 and tubes I IJ and I2 may be iixed in the motor piston, for instance in the manner illustrated by Fig. l, according to which tube I2 is rigid with wall 9 which also carries tube I Il, for instance through a weld joint 21.

Partition 9 is itself applied against a circular abutment 28 of partition 4, by means of a nut 29 screwed on a threaded portion of tube I2 and applied against a plate 30 which bears against a shoulder 3| provided on the inner face of partition 4. Apertures 32 provided in tube I2 afford communication between the outlet apertures I of chamber b and the interval between tubes IU and I2.

According to Fig. 2, the motor piston is constituted by elements f and g, element f including piston end wall I, outer cylindrical Wall 2 and transverse partition 5, whereas element g essentially includes inner partition 4, this partition, in the embodiment of Fig. 2, being constituted by the end of rod 26.

Element f is xed on element g by means of bolts 33 one of the ends of which is screwed in wall 5 whereas the other end passes through a ring 34 mounted on rod 26, nuts 35 screwed on the free ends ofr bolts 33 being applied against ring 34.

According to Fig. 2, tube I2 is provided at its inner end with a flange 36 which is applied against a shoulder 3| of element g, under the pressure of bolts and nuts which apply partition 9, which carries tube I0, against another shoulder 31 formed on the inner wall of partition 4. In the embodiment of Fig. 3, the element h of the motor piston includes end wall I and cylindrical wall 2, whereas the element i includes the inner partition 4 and wall 5. These two elements are assembled together by means of bolts 38 which urge toward each other a ring 39 bearing at 40 against element h and partition 9 which 'bearsv upon a shoulder 4I of partition 4. The whole of h andi zis` fixed, for instancel by means of bolts,

5. on a flange 42 of rod 26, upon the end' of which' conduit I2 is also fixed at 43,while conduit I0, as in the` preceding embodiment, is fixed in'partition 9.

In the embodiment shown by FigA, the motor piston is constituted by three main elements:

1. An element y' which constitutes the central portion of the piston end wall;

2.V `An element 7c which constitutes the peripheral portion of the piston end walland also side wall 2 and wall 5, this element further including a frusto-conical extension 44 which forms a housing for the element y' of the piston end wall;

3. An element Z which forms the inner partition.

4 of the piston and includes a flange 45 through which the end of hollow rod 26 and an intermediate piece 46 acting as a supportrfor conduit I Z are fixed, for instance by means of bolts. n

The three elements y, 1c and l are connected together by means of bolts 41 screwed at one of their ends in element y' and bearing, through nuts fixed on their other end, against partition 9 which bears against a shoulder 48 provided on element Z, the inner edge of the frusto-conical portion 44 of element lc being thus tightly held against elements :i and Z.

It should be noted that the expression free piston is meant to include not only apiston both of the dead center points of which are variable but also a piston only one dead center point of which, in particular the inner one, is variable.

In a general manner, while we have, in the above description, disclosed what we deem to be practical and efficient embodiments of our invention, it should be well understood that we do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What we claim is:

1. An internal combustion engine piston which comprises, in combination, a cylindrical wall, an end wall transverse to the axis of said cylindrical wall, a cylindrical partition coaxial with said cylindrical wall on the inside thereof and extending from said end wall to a distance therefrom, a transverse partition extending from said cylindrical wall tc said cylindrical partition at the end thereof located at a distance from said piston end wall, whereby an annular chamber for a cooling liquid is formed between said cylindrical wall, said cylindrical partition, said piston end wall and said transverse partition, a second transverse partition extending across said cylindrical partition and on the inside thereof at a place intermediate between the piston end wall and the first mentioned transverse partition, whereby a central chamber is formed between said cylindrical partition, said piston end Wall and said second transverse partition, means for feeding cooling liquid into said central chamber, the cylindrical partition being provided with at least one inlet aperture connecting said central chamber with said annular chamber, said aperture being located at a distance from the piston end wall, said cylindrical partition being also provided with at least one outlet aperture located between said two transverse partitions and at a distance from the first transverse partition, and means for letting out cooling fluid from said second mentioned aperture.

2. An internal combustion engine piston which endiwalltransverseto thev axis of said cylindrical wall, a cylindrical partition coaxial with said cylindrical wall on the inside thereof and extending from said endwall to a distance therefrom, a transverse partition extending from said cylindrical wall to said cylindrical partitionat the end thereof located at a distance from said-.piston end wall, whereby an annular chamber for a cooling liquid is formed between said cylindrical wall, said cylindrical partition, said piston end wall and said transverse'partition, a second transverse partition extending across said cylindrical partition and on the inside thereof at a place intermediate between the piston end wall and the first mentioned transverse partition, whereby a central chamber' is formed between said cylindrical partition, said pistonencl wall and said second trans'- verse partition, an axial conduit extending through said second transverse partition and pro'- jecting therefrom'to a distance inside saidA central chamber for feeding cooling liquid into'said central chamber, the cylindrical partition being provided'with at least one inlet aperture' connectingsaid central. chamber with said annular chamber, said aperture being located at a distance from the piston end wall, said cylindrical partition being also `provided with at least one outlet aperture located between said two transverse partitions and at a distance from the first transverse partition, and an outflow conduit coaxially surrounding said flrst mentioned conduit for letting out cooling fluid from said second mentioned aperture.

3. An internal combustion engine which comprises, in combination, a frame, a motor piston mounted to reciprocate wtih respect to said frame and including a cylindrical wall, an end wall transverse to the axis of said cylindrical wall, a cylindrical partition coaxial with said cylindrical wall on the inside thereof and extending from said end wall to a distance therefrom, a transverse partitionextending from said cylindrical wall to said cylindrical partition at the end thereof located at a distance from said piston end wall, whereby an annular chamber for a cooling liquid is formed between said cylindrical wall, said cylindrical partition, said piston end wall and said Itransverse partition, a second transverse partition extending across said cylindrical partition and on the inside thereof at a place intermediate 4between the piston end wall and the first mentioned transverse partition, whereby a central chamber is formed between said cylindrical partition, said piston end wall and said second transverse partition, an axial conduit rigid with said piston extending through said second transverse partition and projecting therefrom to a distance inside said central chamber, a second conduit coaxially surrounding said first mentioned conduit and rigid therewith, means rigid with said frame for feeding cooling fluid into the first mentioned conduit, the cylindrical partition being provided with at least one inlet aperture connecting said central chamber with said annular chamber, said aperture being located at a distance from the piston end wall, said cylindrical partition being also provided with at least one outlet aperture 1ocated between said two transverse partitions and at a distance from the rst transverse partition, means for connecting said outlet aperture with the annular space between said two coaxial conduits, a conduit rigid with said frame engaging in a fluidtight fashion the outer wall of the seccom-prises, in combination, a cylindrical wall, an ond mentioned conduit, and means for the out- @MANS '7 new fof tooling liquid from the third xmentioned conduit.

4. .im 'intern'al combustion engine piston according '-t'o c1airn`2 further including fa transverse deilectio'n `plate mounted at the :end of Isaid axial conduit loc'ated in said central chamber so fas radially to deflect the ncooling liquid `liotvingfout from said-conduit.

-5. A-n internal combustion engine piston aceording to claim 1 constituted by threefelements kassembled together, `the :first @element forming the central portion ofthe piston end wall and -havin'g a frusto-conicai peripheral edge, the second elei ment forming the vperipheral portion -of said 15nd wall, vthe lateral wall and lthe rst mentioned transverse partition, said `second element including a truste-conical housing adapted to aecommodate lthe peripheral edge yof said rst element, and the third element fforming vthe -cylindrical partition, said `cylindrical partition 'being provided, 'on its inner face, with fa shoulder :adapted :to cooperate with the 'second transverse .partition to prevent ldisplacement thereof with respect to said -cylindrioal xtransmission beyond yagli/en point REFERENCES CITED The following 'references are of record in the le of `this patent:

UNITED STATES PATENTS Number Name Date 1,206,723 McKechnie Nov. 28, 1916 1,615,459 Jorgensen Jan. 25, 1927 1,762,442 Jorgensen June 10, 1930 2,109,060 Dennison Feb. 22', 1938 FOREIGN PATENTS Number y Country Date 243,077 Great Britain of 1925 

